1. Field of the Invention
This invention relates to a gearbox breather outlet and in particular to a gearbox breather outlet suitable for an aircraft mounted gas turbine engine.
2. Background Information
Aircraft mounted gas turbine engines are usually provided with a gearbox which is driven by the engine and provides drive for certain engine accessories. Such gearboxes are oil lubricated and are provided with so-called "breather" outlets to provide communication between the gearbox interior and the exterior of the engine. This is to ensure that the operation of the gearbox does not result in an air pressure build-up within the gearbox casing. Inevitably, operation of the gearbox results in severe agitation of the oil within the gearbox to the extent that an oil mist is usually formed. This oil mist can escape through the gearbox breather outlet and so it is common to provide a centrifuge device in the breather to separate out the oil mist before it is ejected from the engine. Unfortunately such structures are not completely effective in providing the capture of all of the oil mist so that some oil is inevitably lost through the breather outlet. The magnitude of the oil loss under these circumstances is not great and does not normally present any problems in the effective operation of the gearbox. However the oil which is ejected from the breather outlet, which is typically fitted flush with the engine nacelle, tends to cause dark colored stains along the engine nacelle. The problem is particularly acute in the case of nacelles which have a light color.
Such stains are seen as being highly undesirable since they are unsightly and are very difficult and time consuming to remove by normal cleaning methods.